The factorial of a positive integer n, denoted by n!, is the product of all positive integers less than or equal to n. For example, 6! = 1 x 2 x 3 x 4 x 5 x 6 = 720. Below is a python program to identify this number.

 n = input("enter positive integer:")
 if n < 0:
         print "error: you entered negative integer"
 else:
         product = 1
         for i in range(1, n+1):
                 product = product * i
         print n, "!=", product

 

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